Background

Programmed death (ligand)-1 (PD-[L]1) checkpoint inhibitors have demonstrated promising activity for patients with malignant pleural mesothelioma (MPM) in early clinical trials,1,2 leading to the off-label use of pembrolizumab in Switzerland as second- or further-line treatment in patients with MPM. Data from a retrospective registry study on pembrolizumab use in patients with MPM in Switzerland were presented at the ESMO 2017 Annual Congress.3

Study design

This registry study was a retrospective analysis of data on patients with relapsed MPM who received pembrolizumab in 13 cancer centres in Switzerland.

Response outcomes for pembrolizumab were assessed by the local investigators using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

PD-L1 expression was quantified in a central laboratory using antibody SP263 (Ventana).

Key findings

Baseline characteristics and disposition

Data were collected on 48 patients who received pembrolizumab for relapsed MPM between September 2015 and April 2017.

The median age at diagnosis was 68.5 years (range: 25–86), 96% of patients were male, and 18 patients (39%) had an Eastern Cooperative Oncology Group performance status (ECOG PS) ≥2 at the start of pembrolizumab treatment.

Pembrolizumab was the second-line treatment in 31 patients (65%).

Platinum chemotherapy and pemetrexed was given to 46 patients (96%) in a prior line of therapy.

The median time since diagnosis was 8.7 months (interquartile range: 6.9–18.1).

Doses of pembrolizumab included:

10 mg/kg every two weeks (q2w) (5 patients, 10%);

200 mg q2w (1 patient, 2%);

2 mg/kg q2w (4 patients, 8%);

200 mg every three weeks (q3w) (28 patients, 58%); and

2 mg/kg q3w (9 patients, 19%).

The median duration of treatment was 3.0 months (95% CI: 2.7–4.1) and treatment is ongoing in eight patients.

Efficacy

At a median follow-up of 8.8 months, the overall response rate (ORR) in the total population was 25% (1 complete response and 11 partial responses).

The disease control rate (DCR) was 52%, including 13 patients with stable disease.